1. How much can be diverted from the watershed before 
permanent damage is done to the ecosystem? 
2. How much water must be released into the system in 
order to mitigate the negative impact of water quality 
after diversions have produced such damage, and is it 
possible to maintain optimal levels of resources in the 
estuarine system? 
The Sea of Azov provides a comparative example of the 
impact of water withdrawals on the physical and biological 
characteristics of an estuary. In the large body of literature 
produced in the Soviet Union since the 1920s, the Sea of Azov is 
cited as the most productive low salinity region in the world. 
According to Zenkevich (1963, p. 465) the total fish catch was 
80 kg/hectare in some years. The case history of the Sea of 
Azov is strong evidence in support of the concept that fresh¬ 
water inflow from its two main rivers, the Don and Kuban, plays 
a major role in maintaining the biological productivity of the 
Sea and its estuarine systems (GOIN, 1972; Bronfman, 1971; 
Volovic, 1986). 
The purpose of this research is to: (1) examine the 
changes in the San Francisco Bay and the Sea of Azov ecosystems 
(Table 1 and Figure 1) associated with freshwater diversion 
patterns between 1921-1978; (2) analyze the relationship between 
the modification of annual and seasonal river inflow, the water 
quality of the ecosystem, and the status of its living and 
non-living resources; and (3) attempt to define the levels of 
river flow needed to meet the freshwater needs of these 
resources while also satisfying the requirements of California's 
agricultural, industrial, and municipal users. 
The following data have been used in our analyses: 
1. Monthly and annual natural and regulated river inflow 
to the Delta, and the corresponding Delta outflow to 
the Bay, for the period 1921-1978 (California 
Department of Water Resources 1980; Kelley and Tippets, 
1977). 
2. Commercial and sport catches of anadromous fish 
(striped bass [Mprqne saxatilis], and shad [Alosa 
sapidissima l. from 1884 to 1982 (Skinner, 1962; 
California Department of Fish and Game, 1983). 
3. Monthly and annual values of combined natural and 
regulated river inflow to the Sea of Azov, salinity of 
sea water, and commercial catch records (1930-1980) of 
major species of anadromous fish (publications of the 
Ministry of Fisheries of the U.S.S.R., All Union Insti¬ 
tute of Fisheries and Oceanography, and the Azov-Black 
Sea Institute of Fishery and other sources). 
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